Rivets are common components, of elongate form, making it possible to assemble for example two sheets of metal one against the other. The rivet is inserted into a hole pierced in the assembly of the two sheets of metal to make it possible to achieve “blind” assembly, that is to say solely by manipulations on the projecting part of the rivet, most often by pulling on the stem.
Common rivets are metallic and comprises a pulling stem of steel provided at one of its ends with a head, and also comprising a sleeve of aluminum also provided with a head, the sleeve being joined to the pulling stem such that said heads are spaced apart from each other.
This type of rivet is inserted, by the head of the pulling stem, into a hole passing through an assembly, that head projecting from the other side of the assembly, and then the pulling stem is pulled with respect to the head of the sleeve, which bears on the assembly, until the head of the stem deforms the body of the sleeve while tightening the members of the assembly against each other, between the head of the sleeve and the body of the deformed sleeve.
Other known rivets are in plastics material, which for example avoids them having to be removed from parts made of plastics material destined to be recycled.
These plastics rivets have the same form as corresponding rivets in steel-aluminum with the sole difference being that the sleeve generally comprises a tooth adapted to cooperate with notched portion on the pulling stem, close to the head, in order to maintain the tightened position after the stem has been pulled.
Although these known rivets are satisfactory in the performance of their function, they require to be manufactured from two different types of material on account of the different properties necessitated for the pulling stem (hardness, low plastic deformation, etc.) and for the sleeve (ductility, considerable plastic deformation, etc.).